Cartilage Homeostasis and Osteoarthritis

Abstract

Healthy limb joints are important for maintaining health and attaining longevity. Endo-chondral ossification (the replacement of cartilage with bone, occurring during skeletal develop-ment) is essential for bone formation, especially in long-axis bones. In contrast to endochondral os-sification, chondrocyte populations in articular cartilage persist and maintain joint tissue into adult-hood. Articular cartilage, a connective tissue consisting of chondrocytes and their surrounding extracellular matrices, plays an essential role in the mechanical cushioning of joints in postnatal loco-motion. Osteoarthritis (OA) pathology relates to disruptions in the balance between anabolic and catabolic signals, that is, the loss of chondrocyte homeostasis due to aging or overuse of cartilages. The onset of OA increases with age, shortening a person’s healthy life expectancy. Although many people with OA experience pain, the mainstay of treatment is symptomatic therapy, and no funda-mental treatment has yet been established. To establish regenerative or preventative therapies for cartilage diseases, further understanding of the mechanisms of cartilage development, morphosis, and homeostasis is required. In this review, we describe the general development of cartilage and OA pathology, followed by a discussion on anabolic and catabolic signals in cartilage homeostasis, mainly microRNAs.